Method of reducing digital images

摘要

An image binarization system in which the threshold value used for the binarization process can be adjusted to thereby enable the process to be made more accurate and avoid loss of black areas in characters in the process of digitizing and conversion. The threshold value is based on the average value of pixel density values around the pixels to be binarized, and is corrected downward when the average density value of the surrounding pixels is larger than a specific boundary value, and upward when the average value is smaller than the said boundary value.